Arsene Wenger described how Olivier Giroud promised he would hit the winner before his special effort snatched Arsenal a Europa League win at Red Star Belgrade.

After 85 tepid minutes at the Rajko Mitic Stadium, Jack Wilshere's burst through midfield, one-two with Theo Walcott and the winger's centred header set up Giroud to score a brilliant overhead kick and maintain the Gunners 100 per cent run in Europe this term.

The Frenchman had looked well off the pace before his stunning intervention, and his manager believes the ability to remain interested in the contest sums up Giroud's mentality.

"At some stage, he came to the touchline and told me we will score. That's Giroud, he keeps belief when it's tough," Wenger told reporters.

"That's why he scores at moments you do not expect him to score."

Wenger returned to a 3-4-3 formation, with Mohamed Elneny playing alongside forgotten man Mathieu Debuchy at the back, while Under-23 attacking star Reiss Nelson was crowbarred in at wing-back.

The slightly odd look to the team resulted in a jittery performance and Wenger said his side's fighting spirit was key to victory.

"It was a very difficult game – with high intensity," Wenger added. "We kept going and tried to win the game, they did as well in fairness. [Petr] Cech made some good saves.

"We got a win that gives credit to the mentality of the team.

"I believe you win when you can – you do not decide when. What is remarkable is the spirit we have shown, fighting together.

"They defended very well, but the goal is a consequence of us wanting to play through them."